Hot-air heating system



Nov. 24,1925.

D. A. BRUNETT HOT AIR HEATING SYSTEM 5 Sheet's-Sheet l Filed May 5, 1923D. A. BRUNETT HOT AIR HEATING SYSTEM Filed May 5, 1923 Sheets-Sheet 2Nov. 24 1925' D. A. BRUNETT HOT AIR HEATING SYSTEM Filed May 5, 1925 5SheetsSheet 5 Nov. 24, 1925.

D. A. BRUNETT HOT AIR HEATING SYSTEM Filed May 5, 1923 5 Sheets-#Sheet 4i. 0 T N E V N I Nov. 24,1925. 1,562,737

D. A. BRUNETT HOT AIR HEATING SYSTEM Filed May 5, 1923 5 Sheets-Sheet 5u j j k Patented Nov. 24, 1925,

UNITED STATES DEWITT A. BRUNETT, OF MINNEAPOLIS, MINNESOTA.

HOT-AIR HE TING SYSTEM.

Application led May 3,

To all 'whom it may concern:

Be it known that I. Dnwrrr A. BnUNn'r'r, a citizen of the United States,residing at Minneapolis, in the county of Hennepm and State ofMinnesota, have invent-ed certain new and useful Improvements in Hot-AirHeating Systems; and I do hereby declare the following to be a full,clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame.

This invention relates to a warm air heat-- ing system and particularlyto such a system including a furnace and a warm air auxiliary heatingdevice in connection therewith. In warm air furnaces and auxiliaryheating devices as heretofore constructed, there has often been a greatdeal of the heat from the fuel wasted by passing up the chimney and thewarm air which is passed to the building to be heated has not beeneffectivelyv brought into contact with the heating surfaces containingthe hot products of combustion.

It is an object of this invention, therefore, to provide an auxiliaryheating device comprising a secondary combustion chamber having meansconnecting it to the combustion chamber of a furnace and having apassage for descending cold air around or at the exterior thereof and aplurality of passages for ascending warm air at the interior thereof.

It is also an object of the invention to so proportion the number andsize of said passages for ascending warm air that the cross-sectionalarea thereof will have a definite rat-io to the grate area of thefurnace and to the amount of heating surface with which the warm aircomes in contact, whatever the size of the device.

Itis a further object of the invention to provide such a secondarycombustion chamber, as stated, with a passage for descending cold air atthe exterior thereof and a passage for warm air at the interior thereof,together with a skirt forming partition spaced slightly from theexterior wall of the secondary combustion chamber and forming a passagefor ascendingvwarm air which conimunicates at its top with said firstmentioned passage for ascending warm air.

It is still another object of the invention to provide a device havingsuch a secondary combustion chamber as set forth which has means at oneside Aand at the upper portion thereof connecting it to the combustion1923. serial No. cae-414.

chamber of a furnace and which has a transverse partition adjacent itslower end eX- tending almost entirely around the same but having anopening therethrough 011 the opposite side of said secondary combustionchamber, which chamber also has an opening below said partitionl andatthe first mentioned side thereof communicating with a smoke pipe.

It is also an object of the invention to provide a device having such asecondary combustion chamber as set forth, preferably of annular shapewhich may surround the combustion chamber ,of a furnace and which willthen. have conduit-s connecting the same to the furnace below the gratebars thereof whereby the products of combustion from the primarycombustion chamber of the furnace will descend in said secondarycombustion chamber and be again circulated through the tire and theprimary combustion chamber.

It is a still further object of the invention. to provide a devicehaving such a secondary combustion chamber connected to the combustionchamber of a furnace adjacent its upper end and having at its lowerportion a conduit connecting the same to a smoke pipe,

which smoke pipe has walls exposed to tho hot gaseous products ofcombustion in said secondary combustion chamber whereby the said gaseousproducts of combustion will descend in said secondary combustion chamberand will be cooled and will pass into said smoke pipe and then bere-heated by the walls of said smoke pipe being in contact with the hotgases in. said secondary combust-ion chamber. In this manner the heatnecessary for draft purposes is transmitted to the gases passing throughthe chimney by radiation and the draft power of the gases due to theheat transmitted thereto will be proportional to the heat required inthe heating system.

It is still another object of the invention to provide a device having asecondary combustion chamber and a smoke pipe in relation thereto, asabove set forth, together with a damper-equipped passage opening intosaid smoke pipe at the upper portion of said secondary combustionchamber and, together with a damper disposed adjacent the lower end ofsaid smoke pipe, which end communicates with the lower end of saidsecondary combustion chamber. i

These and other objects and advantages of the invention will be fullyset forth in the following description made in connection with the accomanying drawings in which like reference c aracters refer to the.- sameparts throughout the different views, and in which,

Fig. 1 is a vertical central section throuffh a `furnace having theauxiliary heating evice applied thereto;

Fig'. 2 is a central vertical sectionr through' said furnace taken in aplane at right angles to the section shown inA Fig. 1;

Fig. 3 is a horizontal section taken on the line 3-3 of Fig. 2, asindicatedvby the arrows;

Fig. 4 is a horizontal section taken on the line'4-4 of Fig. 2, asindicated by the arrows;

Fig. 5 is a partial horizontal section similar to that shown in Fig.- 3but 'showing a modified form of the invention;

Fig. 6 is also a horizontal section similar to that shown in Fig. 3, butshowing a further modified form of the invention;

Fig. 7 is a vertical central section through an auxiliary heating deviceformed as a separate unit from the furnace; and

Fig. 8 is a horizontal section taken on the line 8-8 of Fig. 7

Referring to the drawings, particularly Figs. 1 to 4, a. furnace isshown which may be of any desired type but which, in the embodiment ofthe invention illustrated, is shown as a hot air furnace. This furnacecomprises a base member 1 shown as having a central circular flange atthe inside thereof with which contacts an u standing cylinder 2 formingthe ash pit o the furnace and which supports .at its upper edge a ring3` which carries the grate bars 4. An upwardly flaring fire pot 5 issupported on ring 3 and extends upwardly therefrom having a groovedshoulder adjacent its upper edge adapted to support a cylindrical casing6 having a closing top wall 7,'whieh casing forms the primary combustionchamber of the furnace. The base member 1 is provided with an outerupstanding flange at its upper side having secured thereto andupstanding therefrom the outer cylindrical shell or casing 8 which issecured at its upper end to a downwardly extending flange formed on atop plate 9 of the furnace, which plate is shown as extending slightlyoutwardly beyond the casing 8. An annular-casing 10 partially surroundsthe casing 6, fire pot 5 and ash pit 2 and is spaced from the walls ofsaid parts to form an annular assage 11. The chamber at theinterior ocasing 1f? forms a secondary combustion chamber and is connected to therimaryv 'combustion chamber formed by casing 6 by means coinprising theconduit 12. The casing 10, as shown in Figs. 3 and 4, terminates in endwalls 13 at the front of the furnace and a short section of casing orcurved member 14 1s secured to said end walls and extends around thefront of the casing 6. At the rear of the furnace, the casing 1Q has itsouter walls extending rearwardly in the portions 15 and has-an offsetouter wall portion 16 connecting the portions 15. A transverse partition17 shown as being disposed substantially' horizontal extends across thelower portion of the casing 10 for the greater part thereof andlterminates at each side of said casing in the ends 18 which areadjacent the end walls 13 of said casing. A smoke pipe 19 extendsthrough the top of the easing 1U at the rear thereof between the wallportions 15 and projects downward in said casing through the partition17 and. to a point adjacent the bottom of said casing, as clear-l",Ishown in Fig. 1. The smoke pipe 19 is provided with a damper 20 adjacentits lower end operated by a rod 21 and arms 22, which latter has ahandle extending to the outside i of the furnace (not shown). The smoke'pipe 19 is also provided with an opening .opposite the conduit 12,which opening is closed lor opened more or less by means of a hingeddamper r23 .having an operating.

handle-equipped arm 24 which extends to the exterior of the furnace, asshown in Fig. 1. The space between casings 6 and 10 forms a passage forascending warm air and said space is dlvided into aplurality of pas`- lspaced relation to the wall 14, said double.

wall, however, being shown as terminating at the wall portions 15 of thecasing 10. The upper portion of the walls -26 incline inwardly towardthe center of the cover plate 9 and the inner one of said walls isprovided with a plurality of apertures 27.

The furnace is provided with the usualv charging passage formed by thecasing 28 extending through the front of walls 14 and 26 and through theouter shell 8 which latter is illustrated as being flat orextending in aplane at the front of the furnace. The said casing 28 has a fire door 29hinged thereto provided with a draft opening 30 adjacent its lower edgeopening into a space formed in the door by a vertical partition 31,which latter has a plurality of openings 32 extending therethrough. Thecover 9 has a plurality of circumferentially.y arranged openingstherethrough in which terminate the cou- Vsiderably wider than thecasing 10.

duits 33 which lead to the rooms of the building` to be heated and eachof which com passages 35 receive the warm air ascending to the rooms tobe heated and these passages communicate with the passages formedbetween the partitions 25 and the casings 6 and 10. The ash pit formedby casing 2 is provided with a suitable ash door 36 hinged to the outershell 8 and an o eratin mechanism including a square enlded roi? 37 andgears 38 are illustrated for operating the grate bars. The casingforming the ash pit is also connected to the lower portion of casing 10by circumferentially spaced conduits 39.

The furnace is illustrated as `provided with a humidifying device whichincludesa U-shaped pipe or conduit 40 extending around the rear of theash pit, which conduit has connected thereto the vertical pipes 41opening at their upper ends. Water is supplied to t-he conduit 4() by apipe 41 extending therefrom to the exterior of the shell 8 where it isconnected with a water receiving receptacle 42 having a hinge cover 43thereon, which receptacle, as shown in dotted lines in Fig. 2, is ofless height thanl the pipes 41. The furnace is provided with a clean-outopening 44 for the casing 10 which normally is closed by a hinge gravitydoor 45.

In the modification shown in Fig. 5, the casing 6 is shown having theconduit 12 connecting the same to the annular casing 46 corresponding tothe casing 10 in Figs. 1 to 4. The outer shell 8 is shown together withthe clean-out passage 44 and door 45, which passage communicates withthe casing 46. A single wall 47 corresponding to the double wall 26passes around the exterior of casing 46 and the casing 46 is con- Asmoke pipe 48 passes through the casing 46 in the same manner as thesmoke pipe 19 passes through the casing 10. Circumferentially spacedsemi-annular conduits extend through the casing 46, which latter casingforms the secondary combustion chamber and these conduits open at theupper and lower portions of the casing 10, thus communicating at thelower ends with a space between the casing 46 and the shell 8 and attheir upper ends with the spaces between casing 46 and casing 6.Circular partition walls 50 extend between the conduits 49 and connectthe same and the smoke pipe 48.

In the modification shown in Fig. 6, the casing 6 and conduit 12leadingn therefrom are illustrated, together 'with the outer shell 8 andthe cleanout casing and door 44 and 45, respectively. The secondarycombustion chamber is formed by a casing 51 and a single wall partition52 extends down around the exterior of casing 51, in the same manner asthe double wall partition 26 extends around the casing 10. The cas* ing51 has extending therethrough a smoke pipe 54 having the same relationthereto that the smoke pipe 19 has to the casing 10.

A plurality of cylindrical conduits 53 extend vertically entirelythrough the casing v51 having their open ends at the top and bottomwalls thereof The lower ends of these conduits thus communicate with thespace between wall 52 and shell 8 and the upper ends of said conduitscommunicate with the space between casing 51 and casing 6.

The auxiliary heat-ing device of this inventioncan also be employed as aunit separate from the furnace andsuch an embodiment of the invention isillustrated in Figs. 7 and 8. Referring to said figures, the auxiliarydevice comprises the base 55 and the top 56. The base has an annularflange projecting from the upper side thereof and secured thereto towhich is secured the outer shell 57 which, at its upper end is securedto a flange projecting downwardly from the plate 56. The secondarycombustion chamber is formed by an annular casing 58 disposed centrallyin the shell 57, the central chamber through wliich,.is divided.

by a central partition 59. into separate passages 60 and 61. The casing58 is connected to the combustion chamber of a furnace 67, a p-art ofwhich is indicated in Fig. 8 by a conduit 68. The casing 58 also has anoffset extension 69 adjacent its bottom on the side opposite the conduit68 and a smoke pipe 70 extends upwardly through the casing 58 andthrough the top plate 56 and communicates with the chimney. .The smokepipe 70 terminates adjacent the 'oottom of the casing 58 in the samemanner as the smoke pipe 19 terminates near the bottom of casing 10, asshown in Fig. l and the smoke pipe 7 O will be provided with a suitabledamper 80 such as shown at'2()v in Fig. 1. A door-equipped clean-outpassage 71 is also provided adjacent the bottom of the shell 57extending into the casing 58. The casing 58 is also provided with acleaning device comprising a. member formed by rings 72 adaptedsubstantially to fit against. the inside walls of casing 58, which ringsare connected` by spaced bars or rods 73 to form a rigid frame. Flexiblemembers 74' are connected to certain of the rods 73 and extend upthrough the casing 58 and into pipes 75 having curved bends, which pipesmerge into a common pipe extending through the shell 57 and said flex-'handle correspondingto the partitions '26 in- Figs.

j ly to 4 extends about the exterior of'casing 58 and is slightlyspacedtherefrom, said partition extending almost to the bottom .e of casing58. The vcover plate 56, like the plate 9 has a plurality ofcircumferentially l-arranged openings with which communicate theconduits 63 which lead to the r )oms of the buildings to be heated.

These conduits are each divided by a partition 64 to form -afpas'sage 65for des"ending cold air andra passage 66 for ascendingr warm air and passages 65 communicate with the space between partition 62 and shell 57,'the partition G2 being co-ntinued upwardly 4to meet the partition 64.The passages 66 communicate with the passages 61 andGO which are forascending` warm air. y

In operation of the device, as shown in Figs. 1 and 2, the furnace shownwill be operated as usual with the fire carried in lire pot 5 onthegngrate 4. In starting the fire the damper 20 preferably will beclosed and the damper `23 opened so as to get a direct and strong draftthrough the chimney. Af-A ter the fire is well started, the damper 23 isclosed and the damper 20 opened to a greater or less degree. The hotgases of combustion pass from the primary combustion chamber formed inthe casing 6 through the conduit 12 into the secondary combustionvchamber of casing 10. These gases ,pass downwardly through said casingand must pass around to the end portions 18 of partition 1 7. They thenpass under said partition and aroundtothe rear of the casing 10 and canthen enter the lower end of the smoke .pipe 19. `In their passage downthrough the casing 10 the gases are much cooled so that vpractically allof the available heat has been extracted therefrom. As the gases rise,however, insmoke pipe 19, they are again heated, ydue to the fact thatthe smoke pipe passes through the upper portion of casing 10 where thegases are quite hot and received directly from the primary combustionchamber. A sufficient amount of heat' is thus transmitted to the gasesin smoke vthe burning fuel and this amount of heat will be regulated byadjustment of damper 20. 4The greater the amount of air allowed to passout through the smoke pipe 19, the greater will be the combustion offuel and the greater will be the amount of heat generated. As more heatis generated the smoke Jip@ 19 will heated to a. greater degree y thehot roducts of combustion and a corresponding ygreater draft will becreated.

It will. thus bel seen that draft will -be created, as desired, and thefurnace 'can be regulated to produce the necessary heat in all degreesof weather. The amount of surface Vnecessary to create the required heatfor the draft. can be determined in the con struction ofthe furnace sothat the proper draft will be created at all times. The heat for thedraft is thus created by -radiation and it is more feasible and a greatdeal more eicient from a practical standpoint to extract the heat fromthe gases and then put back the necessary amountfor draft purposes thanit is to attempt to regulate the.

heat going to the chimney direct. Another` '3f test and continuallycooled and contracted resulted in great difficulty in properly reg--ulating the draft.

It is desirable for the warm air furnace to have a humidifier and in theembodiment of the invention illustrated the water will be placed in thetank 42 and may be regulated therein from the city water supply bysuitable controlling mechanism. The water will pass through the pipe 41ninto pipe 40 and rise in the pipes 41to the level of the water in tank42. The heat from the tire box and ash pit will evaporate sufficientwater s0 that the vapor will pass out with the warm air. If for anyreason the water control should get out of order, the water would firstrun out of tank 42 which is at a lower level than the pipes 41 so thatthe trouble would be discovered quickly and the furnace would not beflooded.

The auxiliary heating device, as stated, may also be formed as aseparate unit, as shown in Figs. 7 and 8. The hot gases of combustionpass into the secondary combustion chamber or casing 58 and passdownwardly therethrough and into the lower end of the smoke pip-e 70.The gases will be cooled in their descent so that, as in the other`modification described, they will enter the bottom of the smoke pipe insubstantially cooled condition and will be reheated as they pass upwardtherethrough. This, as above described, furnishes the necessary draftpower. The cooled air from the rooms passes down between walls 62 andshell 57 and the bulk thereof then passes into the lOll passages and 61where it is heated by the secondary combustion chamber 5.8 and passesout throu h the warm air .conduit 66. The partition 62 functions'similarly yto the partition 26 already described and causes the upwardcurrent of air adjacent thereto to travel oppositely to the downcomingheated products of combustion and this partition also presents excessiveheating of the downcoming obviously the same as that of the auxiliaryheater applied directly to the furnace.

The cold air returning from the building descends through the conduits34 and down through the space between walls 26 and shell 8. The greaterbulk of this air passes around the bottom of casing 10 and upwardlythrough the passages in the chamber 11 which are formed by thepartitions 25. This air will thus be efficiently heated by contact withthe `walls of the casings 6 and 10. In order to have theV currents ofthe products of combustion and the air to be heated traveling inopposite directions so that the cold lair comes first in contact withthe coolest heating surfaces, the skirt formed by partitions 26 isprovided. A portion of the cooled air thus passes between walls 26 andthe casing 10 and this cold air will first come into contact with thecooler products of combustion and as it moves upwardly, will comesuccessively in contact with the hotter gases of combustion. The airwill thus be effectively heated. The provision of the skirt partition 26besides giving a morev efficient heating operation for the warm air alsoprevents the descending cold air from absorbing too great an amount ofheat lat the outer portion of the furnace. It is desirable to avoid thisheating of the downcoming air as it merely results in excessiveradiation into the basement containing the furnace and the consequentineffective use or loss of heat. It is for this purpose that the wall 26is made double so that it has a layer of insulating air therein. Theholes 27 are provided so that there may be a very slight circulation ofair between the walls 26 so that the insulating air therein will be keptat comparatively low temperature. When it is desired to carry a very lowfire the air drafts of the furnace will be closed and the damper 20 alsovery nearly closed. The products of. combustion will then circulate downthrough the casing 10 and through the conduits'39 and will again bepassed through the fire. This will result in a complete combustion ofany of the unburned gases and just enough air will be admitted to thefurnace to create sufficient draft to keep the fire going. The damper2() and the hot draft regulating dampers at the front of the furnace canbe automatically regulated by' a thermostat so that the necessary heatcan be provided at all times to maintain the rooms to be heated at thedesired temperature. The partitions 25 result in the air passing to thevarious hot air couduits 35 being equally heated so that one of saidconduits cannot draw more heat from the furnace than another. It is'well known that the fire door of a furnace tends to becomeA quite hotespecially when a deep lire is carried in the furnace. By the provisionof the partition 31, in the fire door, an air space will be formedbetween the same and the outer wall of the door. The plate 31 willbecome quite heated and the "air passing in through the opening 30adjacent the lower edge of the door will thus be heated as it passesupward in contact with plate 31 and will thus pass into the furnace in aheated condition. The air is thus in c0ndition to be more effectivelyburned and the outr wall of the re door is thus also kept coo It will beseen that with a large furnace unit, the cross-sectional area of thewarm `air spaces between casings 6 and 10 will become quite large inproportion to the heating surface and the great area of the furnace. ltis desired therefore in the large units to provide extra heating surfacefor the warm air and this is d one by the modification illustrated inFigs. 5 and 6. In Fig. 5, the conduits 49 are passed through thesecondary combustion chamber '46 and form additional passages for theascend,

ing warm air or additional air heating passages. When these are used,the width of the secondary combustion chamber will be increased. Thesame idea is shown in Fig. 6 in which a great number of smaller conduits53 are passed through the secondary combustion chamber and receive thecold air atfthe bottom thereof and deliver it to the warm lair passagesat the top of the furnace. By providing these additional passages forthe warm air the proper ratio can be maintained between the total crosssectional area of the warm air passages, the grate area of the furnace,and the heating surface with which the warm air contacts. This is verynecessary in order to secure an efficient. heating of the air in `allsizes of installations.

It will thus be seen that applicant has provided a simple and eilcientform of hot air system comprising an auxiliary heating de vice. The heatfrom the products of combustion is` all elfectively used and the prodynace and excessive radiation into the base-` ment. The cost of thefurnace is quite Vsmall owing to the large use of the sheet metalcasings and the. 4furnace can be easily assembled and installed. I l

It will, of course, be understood, that various changes may be made inthe form, details, arrangement and proportions of the parts withoutdeparting from the scope of applicants invention, which, generallystated, consists in the matter shown andvdescribed and set forth in theappended claims.

What is claimed is: Y

1. An auxiliary heating device for a furnace comprising a casing formingavsecondary combustion chamber, means connecting said chamber to theprimary combustion chamber of a furnace, a passage for descending coldair at the exterior'of said secondary combustion chamber, a passage forascending warm air at the interior of said secondary combustion chamberand a skirt artitiolrbetween the exterior of said secon ary combustionchamber and said passage for descending cold air s aced a comparativelysmall distance from t e outerv Wall of said secondary combustion chamberto form a passage for ascending air communicating at its bottom withsaid passage for cold air and at its top with the said passage forascending warm air.

2. The structure set forth in claim 1, and a plurality of conduits forascending warm air assing through said secondary combustlon chambercommunicating kat their lower ends with said passage for descending coldair andat their upper ends with said passa e for ascending Warm air.

3. in auxiliary heating device for a furnace comprising a casing forminga secondary combustion chamber, means adjacent the top portion thereofconnecting the same to the combustion chamber of a-furnace,` saidsecondary combustion chamber having a passage near its bottom leadingtherefrom, and a smoke pipe to which said passage is connected having aportion thereof with a heat conducting wall-passing through saidsecondary combustion chamber whereby the gaseous products of combustionare cooled by their descent in said secondary combustion chamber andwill be re-heated by their passage;l through the smoke pipe. auxiliaryheating evice for a ondary combustion chamber, meansconnecting saidchamber to the primary combustion chamber of a furnace, a passage fordescending cold air at the exterior of Isaid secondary combustionchamber, a passage for ascending warm air at the interior of saidsecondary combustion chamber, and a plurality of spaced conduits forascending warm air passing through said secondary combustionv chambercommunicating at their lower ends with said passage for descending coldair and at their upper ends with said passage for ascending Warm air.

6. In combination with the fire pot, ashpit therebelow and the primarycombustion chamber of a furnace, of a secondary combustion chamberembracing said primary combustion chamber, means at the upper portion ofsaid latter chamber connecting the same to said primary combustionchamber, means connecting said secondary combustion chamber adjacent itsbottom with said ashpit, whereby the gases of combus-- tion will bevcirculated through the fire producing the same.

7. The structure set forth in claim 6, a smoke pipe communicating withsaid secondary combustion chamber adjacent the bottom of the same, andmeans for controlling the passage of gases' into said smoke pipe.

8. An auxiliary heating device comprising a secondary combustionchamber, a smoke pipe communicating with the lower portion thereof,conduits leading to said ddevice from the rooms to be heated, a passagefor descending cold air connected to certain of said conduits anddisposed at the exterior of said secondary combustion chamber, a passagefor ascending warm air connected to other of said conduits and disposedat the interior of said combustion chamber, and means connecting saidseconda combustion chamber to the combustion c amber of a furnace.

9. An auxiliary heating device comprising a casing forminga chamber,means connecting said casing and chamber to the combustion chamber of afurnace, a casing within said first mentioned casing and forming achamber having openings leading to the space to be heated, and aplurality of conduits leading from said last mentioned chamber disposedin and extending downwardly through said first mentioned chamber andhaving lower open ends for the entry of cold air whereby said air isheated as it passes upwardly therethrough.

10. An auxiliary heating device for a furnace comprising a casinghavingr a secondary combustion chamber, means adjacent the top portionthereof connecting the same to the combustion chamber of a furnace, saidchamber having an openingnear its bottom leading therefron'i. and apassage extending upwardly from said opening and connected to thechimney, said passage being at its upper portion 'adjacent said firstmentioned means whereby the products from said eombustiou chamber of thefurnace will heat the gases in said passage.

1l. An auxiliary heating device for a fur nace comprising' a lusinghaving a secondary combustion chaml'ier, means adjacent the top portionthereof connect-ing the sameto the combustion chamber of a furnace` saidchamber having an opening near its bottom leading therefrom, and apassage extending upwardly from said opening` connected to the chimneyand having the Wall thereof passing in front of said means, so that thegases in said passage may beheated by said first mentioned means.

In testimony whereof I aflix my signature.

DEWITT 4A. BRUNETT.

